JP3203735B2 - Hollow fiber membrane module filtration device and its filtration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration apparatus using a hollow fiber membrane module for performing a liquid filtration operation and a method of using the same.

[0002]

2. Description of the Related Art In general, industrial water contains many SS components, fine particles, trash, bacteria, algae, etc. If used as it is, clogging of water pipes, growth of bacteria, line It is likely to cause troubles such as deposition of scale inside. Conventionally, various methods, such as sand filtration, coagulation filtration, coagulation sedimentation treatment, and cartridge filter filtration, have been used in accordance with applications in order to remove these components mixed in water. As a new method replacing these general filtration methods, filtration using a porous hollow fiber membrane has recently been put into practical use. Water treatment and filtration using hollow fiber membranes have rapidly spread in recent years, and their application fields have been expanding year by year.

In the filtration of hollow fiber membranes, thousands to tens of thousands of hollow fiber membranes are bundled into a single bundle and then processed into a product form in which the ends are fixed with an adhesive. Those processed into these product forms are called hollow fiber membrane modules or modules. Many types of hollow fiber membrane modules capable of filtering liquid have been proposed. Particularly as the initial ones, there are a filtration module used in combination with a suitable pretreatment means, one for reverse osmosis filtration, one for dialysis use, and the like.
Many module forms have been proposed for the main purpose of these uses.
-28380, JP-A-49-69550,
Japanese Patent Application Laid-Open No. 53-100176 and the like are described. In all of these, washing or flushing treatment with clear water or chemical solution was usually performed at the stage of disposable use or at the stage where a certain amount of dirt adhered.

[0004] On the other hand, recently, a method has been attempted in which the shape of the hollow fiber membrane module is devised and the adherence on the surface of the hollow fiber membrane is periodically removed by air to recover the performance of the hollow fiber membrane. ing. Japanese Patent Application Laid-Open No. 61-263605 discloses a method in which a hollow fiber membrane is incorporated in a U-shape and used by being housed in a container. Air is periodically introduced from an air inlet provided at a lower portion of the container. The hollow fiber membrane is vibrated by air bubbling to try to remove deposits on the membrane surface. Also, JP-A-60-206415 discloses that
This is a fixed-end module in which hollow fiber membranes are arranged around a central pipe. The module is incorporated in a container in the same manner as in the previous term, and the deposits on the hollow fiber membrane surface are removed by air bubbling. These technologies have already been considered for practical use.

[0005]

In water treatment using a hollow fiber membrane module, it is a good method to remove the deposits on the surface of the hollow fiber membrane by air. However, the deposits on the membrane surface are removed by air bubbling (washing). ), When the filtration operation is started, the accumulation of foreign substances on the membrane surface starts, and the amount of filtered water gradually starts to decrease. Therefore, when the amount of filtered water has decreased to some extent, it is necessary to remove the surface deposits of the hollow fiber membrane again by air bubbling operation or the like. It can also improve the durability of the membrane.
However, in the prior art, since the interval between washings depends on water quality, to increase the interval between washings, that is, to reduce the clogging speed of the hollow fiber membrane, A method was found only to reduce the amount of filtered water per fixed area of the hollow fiber membrane, and in order to consciously extend the interval between washings in normal operation with specified water quality, pressure, flow rate, etc. A good means was required.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heating apparatus for heating raw water , a backwash or air bubbling.
It has a porous hollow fiber membrane module capable washing with
Porous hollow fiber membrane module the filtration apparatus characterized by being, as well, the porous hollow fiber membranes fed to the module rows filtered Utotomoni after was the raw water warmed, the progress of fouling
Porous hollow fiber membrane with backwash or air bubbling
This is basically achieved by a method of filtering water characterized by washing the module .

[0007]

FIGS. 1 and 2 show an embodiment according to the present invention.

[0008] The feed water to be filtered is guided by a pump 2 to a heating facility 4, where the temperature is raised to 20 to 50 ° C.
Next, the supply water whose temperature has been raised is guided to a porous hollow fiber filtration membrane module 6 (hereinafter referred to as a hollow fiber membrane module), where a filtration treatment is performed. In the hollow fiber membrane module, feed water is filtered through countless micropores on the surface of the hollow fiber membrane, and only clear water from which SS components, fine particles, dust, bacteria, etc. have been removed permeates into the hollow fiber membrane. And removed as filtered water. In the filtration of the hollow fiber membrane module, the larger the pressure, the larger the amount of filtered water. However, as the filtration time elapses, the SS component, fine particles, etc. adhere to the membrane surface, and more or less clogging of the hollow fiber membrane occurs. Generally, the amount of filtered water per unit gradually decreases.
Therefore, in order to continue using the hollow fiber membrane module for a long period of time, at an appropriate time when the hollow fiber membrane is clogged and the amount of filtered water is reduced, a cleaning operation such as air bubbling is performed, and the clogging is performed immediately before the clogging. The permeated water amount of the hollow fiber membrane can be recovered to a level.

The method of using the hollow fiber membrane module is not limited, and can be set according to the user's request. Examples of operation methods include an operation method in which the amount of filtered water is changed while keeping the pressure constant, a method in which the amount of filtered water is kept constant while automatically or manually controlling the pressure, and a method in which the module is connected to an appropriate supply water source and the pressure is adjusted. There is a method of operating the vehicle with the temperature as it is.

FIG. 3 shows a change in supply water pressure over time in a conventional hollow fiber membrane module filtration device having no heating equipment, in which the supply water pressure is controlled to keep the flow rate constant. FIG. The pressure gradually rises to cover the decrease in the amount of filtered water due to clogging of the hollow fiber membrane after the passage of the filtration time,
Washing recovers to the state before clogging again, and this cycle is repeated many times.

The present inventors have conducted intensive studies on a method of extending the interval between washings in the operation of this hollow fiber membrane module and continuing to use the hollow fiber membrane module for a long time, and as a result, have found the present invention. It is a thing.

According to the present invention , washing by backwashing or air bubbling having a heating facility for heating raw water is performed.
In a possible porous hollow fiber membrane module filtration device,
By pre-heating the supply water to the hollow fiber membrane module with the heating equipment, the filtration mechanism inside the hollow fiber membrane changes, and even when the same raw water with the same flow rate is filtered by the same module, the hollow fiber membrane is clogged. Has been found to be able to make the generation speed of the extremely low. FIG. 2 is an explanatory diagram of filtration by a filtration device having the heating equipment of the present invention.
The operating conditions are exactly the same as those in FIG. 3 except for the water temperature condition, but the increase in the supply water pressure can be made gradual and the interval between cleanings can be lengthened.

For example, in the case of performing filtration at a constant flow rate using the same hollow fiber membrane module, it can be imagined that the higher the temperature, the lower the viscosity of water, and thus the lower the supply pressure as the initial pressure. In consideration of this point, when the required pressure for cleaning, which is an index required for cleaning, is set to be constant, the higher the temperature is, the lower the initial pressure is, so the pressure difference to the required pressure for cleaning is large, Naturally, it is considered that the cycle until cleaning becomes longer. However, the effect of increasing the temperature does not lie in this point, but as described above, the speed of clogging is significantly reduced. It is many times the effect.

The type of the heating equipment of the present invention is not particularly limited as long as the temperature of the supply water can be raised. A heat exchanger using steam, an electric heating equipment, a steam mixing equipment, and a heat exchange utilizing waste heat are used. Heating equipment that uses generated heat from equipment, rotating equipment, and the like is mentioned as an example.

The heating conditions are that the temperature is 5 ° C. or higher than the raw water, the minimum temperature of the heated water does not fall below 20 ° C., and the temperature fluctuation range of the heated water is 10 ° C. or less. Alternatively, the temperature of the heated water is preferably always 20 to 50 ° C., more preferably about 20 to 35 ° C., and still more preferably 25 to 35 ° C., considering the heat resistance of the hollow fiber membrane material. You can decide.

It should be noted that the "raw water" here is supply water before being heated, and generally can be considered as a temperature close to the outside air temperature. Further, conditions such as “minimum temperature” or “temperature fluctuation range” do not need to be absolutely satisfied, for example, when a filtration operation is not performed, such as when the filtration device is stopped, during washing, or when the filtration operation is performed. Even if it is performed for a very short time, heating need not be performed. Furthermore, the term “always” is not interpreted strictly,
For example, even if the heating device cannot be temporarily heated for a short time, such as when it is necessary to stop the heating device for adjustment or the like, as long as the effect of the present invention is not significantly prolonged, it is of course that there is no particular problem. is there.

By performing the above-mentioned heating, a particularly favorable effect can be obtained in a filtration operation under conditions of low raw water temperature, such as in winter or in a cold region.

[0018] The hollow fiber membrane module of the present invention uses a bundle of porous hollow fiber membranes as a filtering material, and is used for cleaning by air.
Or can be backwashed. Regarding the preferable shape of the hollow fiber membrane module, after sealing both ends or one end of a bundle of many hollow fiber membranes with an adhesive,
It has a structure in which one end or both ends are cut to open a hollow fiber membrane, and is usually housed inside a container as an integral type or a built-in type.

The hollow fiber membrane material constituting the hollow fiber membrane module used in the present invention is not particularly limited as long as it is a porous hollow fiber membrane.
Polysulfone, polyether sulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, and other materials can be selected. Among these, a particularly preferable hollow fiber membrane material is a hollow fiber membrane made of a polymer containing acrylonitrile as at least one component. Among the acrylonitrile-based polymers, the most preferred is acrylonitrile in an amount of at least 50 mol%, preferably at least 60 mol%, and at least one vinyl compound having copolymerizability with respect to the acrylonitrile is at least 50 mol%. , Preferably 0 to 40 mol%
An acrylonitrile-based copolymer consisting of: Also,
It may be a mixture of two or more of these acrylonitrile-based polymers, and a mixture with another polymer. The vinyl compound may be any known compound having copolymerizability to acrylonitrile, and is not particularly limited. Preferred copolymer components include acrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, Examples thereof include vinyl acetate, sodium allylsulfonate, sodium p-styrenesulfonate, and the like.

The next preferred hollow fiber membrane material is a single or two or more olefin polymers such as ethylene propylene or 4-methylpentene, and the surface of the hollow fiber membrane has a major axis of 0.1 to 1 μm. Minor diameter 0.
Those having slit-shaped pores of from 0.5 to 0.5 μm are suitable.

In the case of filtration of a hollow fiber membrane module, the total amount of supply water is generally filtered, but a cross-flow filtration operation for discharging a part of the supply water may be performed without any problem. In addition, it is possible to install a flow control device, a pressure control device, and an automatic cleaning device as needed. Wash Further, the hollow fiber membrane, a method by air bubbling, or by a method (backwash) to the opposite direction through the water filtered water or clarified water from the secondary side of the hollow fiber membrane into the primary side
Cleanse .

[0022]

【Example】

Example 1 A filtration device equipped with a feed water pump, a steam-blowing plate and frame heat exchanger type heating facility, and a hollow fiber filtration membrane module was manufactured. As the hollow fiber membrane module, a polyacrylonitrile porous hollow fiber membrane 1 having an outer diameter of 450 μm, an inner diameter of 320 μm, and an average pore size of 0.01 μm is used.
Both ends of a 2,000 hollow fiber membrane bundle are fixed with an epoxy adhesive, and then one end of the adhesive fixing portion is cut to open the hollow fiber membrane and housed in a container with a diameter of 12 cm. A 100 cm hollow fiber membrane module is used.

Next, using this apparatus, a temperature of 19 ° C. to 2 ° C.
The river water at 0 ° C. was pumped up by a feed water pump and supplied to the heating equipment. After the temperature was raised to 40 ° C. by the heating equipment, the water was supplied to the hollow fiber membrane module to perform a long-term continuous filtration treatment. In the filtration process, the flow rate is adjusted to 10 liters per minute by automatic pressure adjustment. Even if the module is clogged, the pressure rises according to the degree and the predetermined flow rate is maintained. ing. At the start of operation, the pressure at the inlet of the module was 0.25 kg / cm ² , but after the start of operation, the pressure began to gradually increase,
Over time, the pressure reached 1.25 kg / cm ² .
After that, the operation was continued, and after 53 hours in total, the pressure reached the required cleaning pressure of 2.0 kg / cm ^2. As a result of performing the cleaning operation by air bubbling, the differential pressure was reduced to 0.27 kg / cm ^2. Recovered.

Comparative Example 1 The same filtration device as in Example 1 was manufactured except that no heat exchange type heating equipment was installed, and the filtration device was operated under the same conditions. The supply water temperature to the hollow fiber membrane module is from 19 ° C to 21 ° C.
° C. At the start of the filtration operation under these conditions, the pressure at the inlet of the module was 0.75 kg / cm ^2. However, the pressure gradually started to increase after the start of the operation, and after 8 hours, the required cleaning pressure of 2.0 kg / cm ² was reached. having reached cm ² result of performing washing operation by air bubbling, differential pressure 0.
It recovered to 77 kg / cm ² .

[0025]

Industrial Applicability According to the present invention, a hollow fiber membrane capable of removing clogging of a hollow fiber membrane by continuously filtering a liquid containing fine particles and suspended substances and periodically performing air blowing or the like. A modular filtration device and a method of using the same can be provided.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing an example of a filtration apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a change in pressure of the filtration device of the present invention.

FIG. 3 is an explanatory diagram showing a change in pressure of a conventional filtration device.

[Explanation of symbols]

 1: Intake line 2: Supply water pump 3: Normal temperature water line 4: Heating equipment 5: Heating water line 6: Hollow fiber membrane module 7: Waste water valve 8: Air release valve 9: Filtration water line

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-254206 (JP, A) JP-A-61-57290 (JP, A) JP-A-58-95287 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) B01D 63/00-71/82 C02F 1/44

Claims (5)

(57) [Claims] 1. A heating facility for heating raw water , and a backwash
Other porous hollow fiber membrane module the filtration apparatus characterized in that it has a porous hollow fiber membrane module capable washing with air bubbling. 2. A hollow fiber membrane constituting the porous hollow fiber membrane module, porous hollow fiber membrane module according acrylonitrile ing from polymer or olefin polymer and at least one component, the 請 Motomeko 1 Filtration device. 3. A supplied to the porous hollow fiber membrane module after the raw water was heated with a filtration line Utotomoni, the progress of fouling
Porous hollow fiber membrane module by backwashing or air bubbling
A method of filtering water , comprising washing the table . 4. The temperature of the heated water is 5 ° C. lower than the temperature of the raw water.
The filtration method according to claim 3, wherein the heating is performed so as to increase the temperature . 5. The temperature fluctuation range of the heated water is reduced to 10 ° C. or less.
To method of filtering according to claim 3 or 4.